1. Field of the Invention
This invention relates to a rock drill bit advantageously designed to allow efficient cutting and removal of both overburden and rock formations. More particularly, it is concerned with a drill bit having a cylindrical body of uniform diameter with vertically tapered, squared grooves formed thereon.
2. Description of the Prior Art
It is well known that laying pipe in a rock formation presents particular problems. Initially, the rock must be broken into a composition that can be effectively removed by a back-hoe machine. This reduction is accomplished by dynamite. A wagon drill is used to create holes for such dynamite blasting. The wagon drill utilizes a rock drill bit presenting an X-type formation of four carbide cutters, on the bottom thereof, for chipping the rock. Often, one air hole is provided between each of the carbide cutters near the outside of the bit as well as one air hole in the center of the bottom of the bit, for a total of five holes, for blowing out the rock cuttings.
In the conventional drill bits, the carbide cutters extend radially past the periphery of the bit about 1/16 of an inch. The upper two thirds portion of the bit body is smaller than the lower one third portion. Substantially vertical portions about the periphery of the body are cut out to allow the cuttings to be blown up past the bit and out of the hole.
The problem with this design is that it does not deal effectively with overburden (i.e. dirt, mud, clay, shale, sandstone, etc., disposed above the rock formation). When the conventional drill bit is used in a formation containing overburden, the bit does not adequately bore through same. The bit simply pushes the overburden to the side and up over the top of the bit, so that it "collars-up" on (i.e. closes in around) the drill pipe thereby shutting off the hole and preventing the wagon drill from functioning properly. The air holes often become plugged with this overburden and the drill bit may be difficult, if not impossible, to retract from the hole. What is needed is a drill bit which adequately deals with the cutting and elimination of overburden. A number of rock drill bits have been utilized in the past. Patents illustrating these prior units include: U.S. Pat. Nos. 4,385,669, 4,049,066, 3,945,446, 3,605,925, 2,696,973.